It apparently came as a surprise to everybody else involved last weekend when Francisco Liriano revealed that he throws two different sliders — one with a big break and one with a shorter break.

This cleared up the puzzle of why Liriano said earlier in the season that he couldn’t figure out what to throw. The catcher signals for a slider and he’s on the mound thinking which slider?

The immediate solution to Liriano’s surplus of sliders is to junk the short one. (I suppose that when he threw it, everybody else figured it was just a bad slider, not realizing it was deliberate.)

That Liriano had two pitches under the same name harkens to a less sophisticated era of pitching.

For example: Chief Bender — the first Minnesota native to be elected to the Hall of Fame — threw a sharp-breaking pitch he called a curve ball. That same pitch is now known as a slider. The slider didn’t emerge as a distinct offering, with its own name, until sometime in the 1920s.

There were probably pitchers other than Bender to throw the pitch before George Blaeholder claimed it as his own invention. But until the 1920 season, when the spitball and other doctored deliveries were banned, pitchers could rely on the discolored and scuffed balls to provide movement.

Once they were throwing clean balls, they had to find more ways to create movement with their delivery. That continuing search resulted in different names for the results.

Another example: Warren Spahn, the great lefty, won 363 games throwing, among other pitches, a “screwball.” That’s what everybody called it, at least. It was a slow pitch that broke down and away from a right-handed hitter.

That same pitch today? The circle change.

Spahn’s delivery was certainly different than that of Carl Hubbell, another Hall of Fame southpaw, who threw his screwball with a violent twist of the forearm that ultimately left his throwing arm looking as if it had been attached backwards.

Still another: The forkball has been around for decades — another native Minnesotan, Bullet Joe Bush, was the first noted practitioner in the majors back in the 1910s and ’20s. Today, it’s at least as likely to be called the split-finger fastball.

Why the different names? I think it’s intent. The guys who are emphasizing throwing it hard — as Jack Morris did— call it the splitter; the ones who are thinking of it in terms of a change-up — Morris’ former Twins teammate, Mark Guthrie — call it a fork ball.

Then there’s the difference in fastballs. For generations, pitchers spoke of having a “natural” sinking fastball, or a “natural” hop.

It wasn’t until sometime in the 1950s that Curt Simmons, then with the Phillies, realized that he could create different fastballs by changing his grip. Well, maybe it wasn’t Simmons who figured it out — but he appears to have been a key in popularizing the notion and the first to acknowledge having distinct fastballs.

Today, the concept of the “four-seam fastball” — the rising one with greater velocity — and the “two-seam fastball” — also known as a “sinker” — is well known.